'You can't offset your way out of emissions' - for once a Teal gets it right.

Economists say yes. Carrots and sticks are sure to do the job.

Clean electricity is the favourite example for the role of economic measures. With some political encouragement plus the threat of carbon pricing we can now produce clean electricity in more or less unlimited quantities. And clean electricity is expected by many to be the key to clean alternative process routes for every industrial activity.

The big question now is, could all of those 215 businesses eliminate their fossil fuels and emissions by switching to clean electricity? Governments and economists are amongst those who seem to think so. I think they're wrong; there's a genuine feasibility issue.

This opinion may seem at odds with the daily flow of self-congratulatory good news stories about the energy transition. Success in cleaning up the electricity sector does deserve a cheer. But it is best seen as the exception, not the rule.

Cutting emissions from electricity generation has been, relatively speaking, child's play. Clean electricity was first cab off the rank as soon as cutting out fossil fuels became an important aim. We already had the science and early-stage alternative technologies. Wind turbines date from the 19^th century. The first commercial nuclear power generation began in 1957. Research into solar photovoltaic energy conversion was well underway for example half a century ago at the University of New South Wales.

Since those early days there has been a series of huge strides in these technologies. Making abundant clean electricity is now feasible via several technologies. And the prospect of eliminating fossil fuels from electricity generation is now real.

Is the rapid evolution of clean technology for electricity the appropriate model for every industry sector? Could clean electricity be used to displace every application of fossil fuels?

I believe not. Clean electricity can obviously do everything that electricity does now. But that's not everything, by a long shot. In fact, Australian energy statistics show that only 38% of our fossil fuel usage goes towards generating electricity. 62% does not! Most of those 215 businesses are in that 62%.

It is not at all clear why that huge component of fossil fuel usage should somehow be amenable to replacement by electricity. In fact there's a strong case for the opposite. Many or most of those businesses are in existence solely because of fossil fuels. Nitrogenous fertilisers come from ammonia made out of natural gas. Explosives like ANFO, TNT and dynamite essential to the mining industry all originate in fossil fuels. Plastics all come from fossil fuels too. There are thousands of products made from crude oil that rely entirely on that source, especially on the complex organic molecules created by the action over geological time scales of pressure and heat on decaying vegetable matter.

If these essential and valuable products exist almost entirely because fossil fuels exist, and those fossil fuels did not in the early days of that industry replace some other source of energy, then it's quite logical to expect that replacing those fossil fuels could be an overwhelming technical challenge, not feasible at any price. Indeed, looking around it's hard to see such substitution anywhere in the world.

Transportation comprises a separate category. Motion can arise from any energy source converted to mechanical energy to perform work. Electricity does the job well; electric cars using portable stored battery energy have existed for well over a century. A single major breakthrough in battery technology has allowed their dramatic growth. That was not particularly surprising. Battery scientists long expected products based on the lightest metal lithium to do the trick.

Aviation is a tougher nut to crack. It relies on fuels with exceptionally high energy contents (high "specific energy"), liquid fuels now derived from crude oil. Synthetic substitutes are feasible but there is a huge problem of reaching the required scale.